Leakage current and trapped charge characteristics for glass insulator string under contaminated conditions

This paper reports a study on leakage current (LC) and trapped charge characteristics for contaminated glass insulator string. Four units of glass insulators recently removed from service were contaminated according to IEC 60507. The measurement of trapped charge distribution was made by a radially shaped stainless steel mesh surrounding each insulator while LC was measured using 100 Q shunt resistor. The results revealed that as the contamination levels increase, the amplitude of LC increases; but the amplitude of trapped charge decreases.